Sunburn is painful, dangerous and embarrassing. But despite knowing it's the body's protective immune response to high levels of ultraviolet radiation, scientists weren't exactly sure what the biological process behind it was. Turns out that it's your RNA screaming out in pain—a finding which could help sunburn and other skin ailments for good.

Researchers from the University of California, San Diego School of Medicine have shown that the distinctive red glow is a consequence of RNA damage to skin cells. The research is published in Nature Medicine.

Using both human and mouse skin cell models, the researchers found that UVB radiation causes strands of micro-RNA to fracture and tangle. In turn the cells that have been subjected to too much radiation release the RNA, causing a cascading effect where neighboring cells begin to do the same. The net result is an inflammatory response which is intended to remove sun-damaged cells—and that's the sunburn feeling we know and love. Richard L. Gallo, one of the researchers, explains:

"Genetics is closely linked to the ability to defend against UV damage and develop skin cancers. We know in our mouse genetic models that specific genes will change how the mice get sunburn. Humans have similar genes, but it is not known if people have mutations in these genes that affect their sun response."

However, while some mysteries remain, the researchers hope that the new-found understanding should help them eventually block the inflammatory process altogether. "Some people have excess sensitivity to UV light, patients with lupus, for example," explains Gallo. "We are exploring if we can help them by blocking the pathway we discovered."

The same development could make way for more effective treatment of diseases like psoriasis, too, which are usually treated through UV exposure. "Our discovery suggests a way to get the beneficial effects of UV therapy without actually exposing our patients to the harmful UV light," continues Gallo. Oh, and if that weren't enough, working out how to shut down the inflammation means one thing: No. More. Sunburn. [Nature Medicine, Science Daily]